Developing Solar Projects CARES Conference 2019
Assessing buildings for Solar PV Ben Whittle, Welsh Government Energy Service (EST)
What are you trying to achieve? Maximum generation possible? 100% provision plus export? “Reasonable” cover of consumption and minimal export? Will you be adding more electricity consuming equipment later (heat pumps,
What are you trying to achieve?
What are you trying to achieve?
What are you trying to achieve? Small sites – very straightforward Mostly limited by roof size or grid connection (And profitability) Large sites – can be more complicated Export limitation, Constraints, profitability
What are you trying to achieve? Small sites – schools, community centres etc Generally you will want to fill the roof up as the more you install the better value for money you get You will probably be restricted to the statutory limits especially in very rural areas. Commercial supplies are rare, so typically 4kW max.
What are you trying to achieve? Large sites – can be more complicated Constraints Export limitation EV Charging Heat pumps profitability
Why can’t I have nice things?
Why can’t I have nice things? This is called the Low Voltage network – Generally the longer the distance from the transformer the smaller the capacity available
Why can’t I have nice things? In a domestic scenario (single phase: house, small school, office etc) this cable is generally 16mm 2 and can carry about 100 amps, protected by a 60 or 80amp fuse. In a commercial scenario you get 3 cables and triple the system size is possible without “reinforcement” (replacing equipment such as cables or transformers) F or technical reasons it’s not possible to let everyone connect large systems without placing strain on the Low Voltage network – it’s also not “fair” – every new installation takes a little of the capacity in the area away.
Sweet spots to keep life simple – Fit & Inform Statutory limits for “Fit and inform” no requirement to seek permission at ≤3.68kW per phase Domestic (single phase) – up to 4.5kW Solar panels connected to a 3.68kW inverter Commercial (3Phase) – up to 12.5kW Solar panels connected to a 10kW inverter
Sweet spots to keep life simple – 30kW <30kW no export meter was required assumed you will self-consume 50% of electricity – this can work out well in low occupation buildings such as schools or village halls. >30kW you needed to measure both import, generation and export, and there is a cost implication to this with additional meter charges. Where you want to install multiple systems in a tight geographical area you need to speak to your DNO as soon as is practical to avoid complications!
The Smart Export Guarantee BEIS mandates that larger electricity suppliers offer small-scale generators a price per kWh for the electricity they export to the grid. Smaller suppliers can opt to voluntarily provide a SEG tariff but must adhere to the rules and guidance associated with the SEG – applies to producers up to 5MW; • Suppliers would determine the tariff per kWh for remuneration How much? • Suppliers would be obliged to provide at least one export tariff; • Electricity exported to the grid from eligible generators must be metered The government is hoping that this will encourage more battery storage on the grid, reducing strain In theory it might also mean reducing output from solar systems at times of high production – will this affect small and large producers equally? RESULTS OF CONSULTATION EXPECTED IN SUMMER TIME
The Smart Export Guarantee Small operators to Large operators
The Smart Export Guarantee
Assessing buildings – Google Earth You can use Google Earth for free, and you can measure things to an accuracy of around +/- 50 cm
Assessing buildings – Google Earth Be aware that the overhead imagery is often dated and 2 dimensional so you may miss details like: Extensions Roof covering and age Shading objects like trees and
Assessing buildings – Google Earth Using simple rules of thumb you can quickly work out rough capacities Depends on pitch of roof: Pitched roofs are about 8-10msq per 1kW Flat roof has much lower density. You normally need to leave a good
Assessing buildings – using Sketchup You can use Trimble Sketchup for free There also free “plug - ins” that can help you automatically insert solar panels. In this case I have used one called “ Skelion ” Very quick – you can do a simple building in less than 5 minutes Only sensible to do initial summaries, you need to get
Assessing buildings – using Sketchup
Assessing buildings – using Helioscope
Assessing buildings – using Helioscope
Assessing buildings – Roof types Flat – asphalt, felt, membrane GRP Materials & Time Corrugated fragile sheeting Time and safety Slate Time Cos t Tile Steel profile Speed & materials
Assessing buildings – Flat roofs Structural strength – ballast can weigh a lot (esp. in windy coastal areas) and it takes a lot of time to move Roof penetrations should be avoided for weather protection Warranties may be voided on new GRP / Membrane roofs (avoidable) Edge protection can be pricy Future cleaning costs may be increased due to access issues / low angle panels
Assessing buildings – Flat roofs
Assessing buildings – fragile roofs Structural strength – Weak and fragile: numerous deaths and serious injuries in the solar industry Replacement often wise as they are typically also very old and in poor condition Incredibly time consuming to install – double the “normal” allowance Framing costs increase
Assessing buildings – fragile roofs
Assessing buildings – slate roofs Structural strength – Slate roofs were never designed for extra Tend to be older buildings / weaker roofs Spare materials required as slates inevitably break Incredibly time consuming to install – double the “normal” allowance Framing costs increase
Assessing buildings – slate roofs
Assessing buildings – steel profile roofs Super quick Very low framing costs Reduce wind lift issues 200kW in 4 days easily achievable
Assessing buildings – Summary Choose buildings with 3 phase power supplies where possible Find the biggest buildings with the easiest roofs to work on Use buildings with high electrical consumption to improve profitability Consider adding EV charging or heat pumps (additional RHI income) to increase electrical use which you can self consume or sell
CARES Conference 2019 – developing solar projects Edinburgh Community Solar Coop Richard Witney – Project Manager
PV system locations ww.edinburghsolar.coop/projects/solar-panel-locations/
The installations BUILDING kWp kWh/yr CO2/yr (T) AINSLIE PARK LEISURE CENTRE 100 81,849 41 BLACKHALL PRIMARY SCHOOL 15 10,876 5 BUCKSTONE PRIMARY SCHOOL 100 67,663 34 CAMERON HOUSE COMMUNITY CENTRE 20 16,290 8 CANAL VIEW PRIMARY SCHOOL 100 81,417 41 CARRICKNOWE PRIMARY SCHOOL 50 40,326 20 CARRICKVALE COMMUNITY CENTRE 30 25,166 13 CLERMISTON PRIMARY SCHOOL 21 17,705 9 CRAIGHALL DAY 30 24,059 12 CRAMOND PRIMARY SCHOOL CURRIE HIGH SCHOOL 133 98,843 49 CURRIE PRIMARY SCHOOL 45 35,337 18 DAVIDSONS MAINS PRIMARY SCHOOL 35 29,087 15 DEAN PARK PRIMARY SCHOOL 83 65,752 33 DRUMBRAE LEISURE CENTRE 50 40,911 20 EAST CRAIGS PRIMARY SCHOOL 50 41,639 21 GYLEMUIR PRIMARY SCHOOL 30 25,343 13 LIBERTON PRIMARY SCHOOL 45 37,229 19 OAKLANDS SPECIAL SCHOOL (NEW) 125 106,206 53 PROSPECT BANK SCHOOL 35 28,366 14 RATHO PRIMARY SCHOOL 70 54,546 27 REDHALL MLD PRIMARY SCHOOL 50 38,847 19 TUMBLES AT PORTOBELLO 125 102,647 51 WARDIE PRIMARY SCHOOL 30 21,748 11 WOODLANDS SCHOOL MLD 20 14,857 7 TOTALS 1,390 1,106,709 554
Project partners • ECSC board – community benefit society • CEC Energy Team • Edinburgh Leisure • Emtec Energy – project manager, designers, 2 x Roofing Teams, 2 x Electrical Teams, structural engineer, scaffolding contractor • Schools – HTs, teachers, business managers, FM, SSSO, SSO, children • ECSC Shareholders • ECSC PM
Financials Feed in tariff & export rate: • Up to 50 kW = 11.71p/kWh (4.32p) • Between 50 kW & 150 kW = 9.98p/kWh (1.99p) • Export rate = 4.91p/kWh • Paid for 20 years • Indexed linked (April 2017) • Phase 2 of project – 11 buildings awaiting pre accreditation to FiT <50kW
Building selection • Electrical use on site – any export expected? • How the building is used all year? – school/community centre/leisure centre • Ongoing access • Age of building – future maintenance or developments nearby • Ease of access for installation • Type of roof – slate/tile/metal/flat • Good on going relationship with building managers/facility team
Contractor selection • MCS & RECC certified • Initial design support – size, generation, financial feasibility • Availability and communication • Understanding your community • Support with building warrants, planning permission, structural designs • Installation teams – in house or subcontractors • Health & Safety • Final handover – explanation of system & supporting O&M documents
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